1. Field of the Invention
This invention relates to an improved packaging machine, especially a continuously operating machine for wrapping articles with a heat shrinkable plastic film or the like, automatically and sequentially.
More particularly the present invention relates to a shock absorbing skip seal mechanism for use in controlling action of a cross head sealer of the wrapping machine to accommodate articles of greater length than previously possible, to provide a mechanism for producing smooth action of the heads of the cross sealer, particularly at the beginning and end of each seal cycle, and to a novel method associated therewithin.
2. Description of the Prior Art
Various packaging machines for wrapping materials automatically and sequentially with heat shrinkable film are available commercially from various manufacturers. However, these machines frequently display problems in achieving synchronization between the cross head seal mechanism and the infeed conveyor, particularly when continuous operating conditions and elongated articles to be packaged are involved. Also, the machines often require frequent and time consuming maintenance and adjustment.
Further, the prior art machines commonly involve complicated procedures and significant down time to change the machine from one operating configuration to another, such as is needed when package size is changed or different bag cut-off lengths are required. Also, prior art machines utilize specialized, costly components.
Still further, prior art machines have been incapable of wrapping packages of any significant length because of mechanical operational constraints produced by the gear driven cross head sealer.
Typically, accommodation of elongated packages has been provided by speeding transport of such package through the cross head sealer station. Such speeded up transport causes stress on the other stations to maintain synchronization at a much more rapid rate of function, inasmuch as the wrapping is a continuous sheet of material until it is severed into packages by the cross head sealer.
As will be described in greater detail hereinafter, the shock absorbing skip seal mechanism of the present invention allows the remaining stations of the packaging machine to operate at optimum speeds and to accommodate elongated packages by maintaining the cross seal heads separated for a specific number of sealing cycles to accommodate a lengthy package, the skip seal mechanism further providing shock absorbing structure for the heads so that they start up and stop smoothly at each seal cycle, decreasing concussive forces and thereby increasing functional longevity.